Most high quality carafes available today include a vacuum insulated glass filler or vacuum bottle. The vacuum bottle, as is well known, is made of an inner liner surrounding by an outer body base relation thereto so as to define a vacuum space. The outer body is sealed to the inner liner to maintain the vacuum and typically, one or more of the outside body and the inside liner, usually the inside liner, is provided with a radiation reflective coating, such as silver plating, to minimize heat lost through radiation. The vacuum bottle thus constructed is in turn housed in a protective container that will typically will have a bottom and an upstanding side wall with a more or less decorative surface and which terminates in a dispensing opening in fluid communication with the interior of the vacuum bottle.
In some cases, a simple stopper and spout assembly will provide the dispensing outlet for the contents of the carafe. In other cases, as for example, in so called “pump pots”, a pumping mechanism is provided in a removable stopper that includes a conduit that extends downwardly into the bottom of the inner liner. By operating a pump contained in the stopper, the interior of the inner liner may be pressurized to expel liquid through the conduit to the dispensing opening.
In either case, the level of liquid within the vacuum bottle cannot be readily judged when the stopper is in place and even with it is removed, the reflective covering makes an accurate determination difficult.
There have, therefore, been a number of proposals for providing a means for ascertaining the quantity of the contents of such a carafe without removing the stopper. For example, Japanese Utility Model No. 2,515,492 provides a conventional pump pot assembly, additionally having an opening near the center of the bottom of the inner liner vacuum bottle. A transparent pipe is connected to such opening and extends vertically along the exterior of the vacuum bottle. The pipe may be viewed through an appropriate window in the outer container and the level of liquid in the carafe ascertained. Another example is illustrated in Japanese Patent Publication No. S61-160830 which is quite similar to the previously identified Japanese utility patent. Users of both of these structures experience difficulty in cleaning the pipe that provides the indication of liquid level. Furthermore, they are complicated to manufacture and accordingly expensive because of the special need to provide openings in the bottom of the vacuum bottle as well as the provision of several additional parts that are necessary to connect the level gauge constituted by the glass pipe to a dispensing opening and to the interior vacuum bottle.
Another proposal is found in Japanese Published Patent Application No. 2002-68324 wherein part of the vacuum bottle is not silvered so that one may view the contents of the vacuum bottle through the non-silvered portion. In order to determine the level of liquid within the vacuum bottle, the same must be in bright light condition or else the stopper must be removed to allow sufficient light to enter the vacuum bottle through the upper opening and/or the unsilvered portion to provide sufficient illumination to accurately judge the liquid level.
Thus, there is a real need for a carafe of the type utilizing a silvered vacuum bottle for insulation purposes that allows an accurate determination of the fill level of the vacuum bottle under widely varying light conditions and provides the ability to do that in an inexpensive construction that does not require the provision of additional holes in the vacuum bottle and eliminates the need for a considerable number of additional parts associated therewith.